Leather, in the course of manufacture, is subjected to various processes to produce leather of an acceptable quality. Among the processes are those for the softening and stretching of leather: so called staking processes. It has been proposed to effect processing of leather, for example staking, by means of two, opposed processing elements between which the leather is through-fed and whose distance apart is increased and decreased periodically by relative movement. The operation of this so-called vibration-type staking equipment has been known for a long time, see for example U.S. Pat. No. 73408 (Tidd) dated Jan. 14, 1868.
More recent work in this field has been concerned with the means by which the material to be processed is transported through the working-zone of the vibration-type staking machine. It has been proposed to provide a vibration-type staking machine having processing elements or tools with projections which interengage in the operation of the machine, in which the leather is fed through the working gap between the tools by means of two elastic conveyor-belts; such a machine is described in German Auslegeschrift No. 1285092 (Strojosvit, Narodni Podnik) dated June 25, 1962 and machines similar to that described in the Auslegeschrift have been used in large numbers.
It has also been proposed to transport the material through the vibration zone by means of an air current, see for example German Patent Application Nos. P 19 14 910.1, P 19 14 964.5, and P 19 14 965.6. However, transportation of the leather through the vibration zone by means of an air current has not proved practical.
It has also been proposed in German Patent Application No. P 22 45 008.4 (Badische Maschinenfabrik GmbH) dated Sept. 14, 1972 to provide a machine having processing tools with projections, one of the tools being fixed in a closed position in the operation of the machine and the other of the tools oscillating, the leather being simply drawn out from between the tools as the said other tool oscillates. To introduce the leather into such a machine the tool which is fixed in a closed position whilst the leather is being processed, is moved to an open position in which it is spaced from the other of the tools: thus machines working on this principle have no conveyor belts. Such machines are used in the trade, however they are not through-feed machines and thus cannot carry out a continuous-processing operation.